Detroit News Columnist Daniel Howes and Michigan Radio are partners in weekly essays examining what's hot in Michigan business and politics – and what it all means. This week, Howes says this week’s criminal indictment of former Volkswagen AG CEO Martin Winterkorn sends a powerful signal to automakers – and corporate bosses around the world. Scheming to evade the Clean Air Act and doing it with vehicles touted as “Clean Diesel” threatens a kind of official retribution that’s likely to keep on giving.